This invention relates to a facsimile apparatus and, more particularly, to a facsimile apparatus constructed to be flat and small in size.
A facsimile apparatus constructed to be small in size has been proposed in the art. The recording section and the original reading section of this facsimile apparatus will now be described with reference to the drawings.
FIG. 26 is a transverse sectional view illustrating a facsimile apparatus according to the prior art. This represents an example of the smallest, flattest arrangement said to be available at the present time. A cover 200 serving also as a casing has a top side provided with a first opening 203 in the vicinity of the edge thereof, and a second opening 204 located further to the rear. The casing cover 200 also has a front side provided with an exit port 205.
In this arrangement, an original G is placed face down and inserted into the first opening 203. The original is conveyed and discharged from the exit port 205 while clamped between a contact-type line image sensor 12 and a first biasing roller 13 rotatively driven in a state biased with respect to the line image sensor 12.
A roll KR of thermosensitive recording paper K2 is replaceably supported in a freely rotatable manner (in the direction indicated by the arrow) on the underside of the cover 200. The recording paper K2 is so arranged that its recording side opposes the recording portion of a line thermal head 140. The recording paper K2 is clamped between the line thermal head 140 and a second biasing roller 150 rotatively driven while biased with respect to the head 140. While thus clamped, the recording paper K2 is discharged to the exterior of the apparatus via the second opening 204 after being recorded on.
By virtue of the configuration described above, the reading section and the recording section are arranged to overlap in the thickness direction of the casing cover 200, thereby making it possible to greatly reduce the thickness of the casing cover 200.
FIG. 27 is a perspective exploded view showing the details of the recording section. As shown in FIG. 27, the line thermal head 140 and the conveyance roller 150 are arranged as illustrated. The line thermal head 140 is secured to a head supporting member 142. The line thermal head 140 is so adapted as to be biased at three locations on its underside by compression springs 120 after it is installed. The coil springs 120 at the two ends are situated so that the distance between them is less than the width of the recording paper.
The positioning mechanism of the line thermal head 140 and conveyance roller 150 constructed as set forth above is the most important component in terms of the recording section. The line thermal head 140 and conveyance roller 150 must be in a stable state at all times and the outer circumferential surface of the roller must contact a printing line (heating element) 152.
Accordingly, in the conventional apparatus, the conveyance roller 150 is freely rotatably supported by bearings 41a, 41b arranged on side plates 40a, 40b. The line thermal head 140 is mounted on a head supporting member 142 machined to have a generally U-shaped configuration, as shown in FIG. 27. Roller biting grooves 143a, 143b provided in side plates of the head supporting member 142 embrace conveyance roller shafts 150a, 150b, respectively, thereby deciding the positional relationship of the line thermal head 140 relative to the conveyance roller 150.
In accordance with this arrangement, the head supporting member 142 and the conveyance roller 150 are maintained in a stable relative positional relationship at all times if the centers of the conveyance roller biting grooves 143a, 143b in both side plates of the head supporting member 142 and the printing line 152 of the line thermal head 140 can be set to lie on a straight line. As a result, the roller 150 can be brought into accurate contact with the printing line 152.
In order to realize a portable facsimile apparatus, downsizing each constituent unit of the apparatus if of paramount importance. Accordingly, with regard first of all to the size of the recording section in the width direction, the minimum required elements are two in number, namely the recording head and the side plates that are for freely rotatably supporting the conveyance roller. An arrangement in which one side plate of the main body, the head and the other side plate of the main body are arranged in the order mentioned in the width direction provides the smallest positioning mechanism.
More specifically, in the conventional facsimile apparatus described above, the side plate 40a of the main body, the head supporting 143a, the head 140, the head supporting member 143b and the side plate 40b of the main body are arranged in the order mentioned in the width direction of the recording section. The thickness of the head supporting members 142 and the dimensions of the clearances needed for installing them are large. This makes it necessary extra width for the relative positioning mechanism of the portable facsimile apparatus.
Further, when the elastic modulus of bending of the thermal head is compared with that of the conveyance roller in the conventional facsimile apparatus, the coefficient of the thermal head is about four times that of the conveyance roller. Therefore, in the case where the thermal head is biased with respect to the conveyance roller by the biasing members, the spring biasing force is high even though the three points are biased solely by the compression springs 120. As a consequence, the conveyance roller adapts itself to the head shape even though the head is in the flexed state so that the thermal head is uniformly biased in its axial direction.
However, in consideration of downsizing as mentioned above, it is better to use a thin-type thermal head that has half the thickness of the conventional apparatus. In such case the elastic modulus of bending of the thermal head will be 1/8 of the conventional apparatus. If this thin-type head is biased by the compression coils spring 120 at the three points in the same way as mentioned above and, moreover, it is biased at a biasing force of 1.5 kg, which is half that of the prior art, the roller 150 will not adapt itself to the shape of the thin thermal head 140. Rather, the thermal head 140 having the low elastic modulus of curvature will adapt itself to the shape of the roller 150.
At such time, when use is made of the head 140 which is in the downwardly flexed state because of use of the compressed coil springs 120 to achieve biasing at three points, the two ends of the head 140 float free of the roller 150. The problem that results is that uniform biasing cannot be achieved in the axial direction, which is indicated by arrow y.
Further, in order to reduce the thickness of the casing in the above-described facsimile apparatus, the roll recording paper KR is disposed between the reading section and the recording section. As a result, it is necessary that the dimensions of the case in the depth direction be made at least large enough to accommodate the roll recording paper KR. Therefore, a problem which arises is that the apparatus cannot be made small in the depth direction.
Furthermore, in order to use the above-described facsimile apparatus as a portable facsimile apparatus, a battery is mounted to serve as the power supply. In such case, a so-called battery pack is employed. However, since the battery pack ordinarily is of such type that it is loaded and unloaded on the outside the casing, the external dimensions of the apparatus increase accordingly.
In accordance with the above-described facsimile apparatus, only rolled recording paper is used as the recording paper; a thermosensitive recording paper in pre-cut sheets, such as size A4, cannot be introduced to the recording section. More specifically, in order to make it possible to introduce pre-cut sheets of recording paper to the recording section, a very troublesome operation is required, such as introducing the pre-cut sheets after the roll recording paper is removed first. This makes it substantially impossible to employ pre-cut sheets. In a case where a special-purpose opening for inserting pre-cut sheets is provided anew near the aforementioned first opening, by way of example, the strength of a rod-shaped partition formed between the first opening and the above-mentioned opening, which has a length at least as great as the A4 width of the pre-cut sheets, cannot be assured. This makes it substantially impossible to set pre-cut sheets in place.
Further, in order to reduce the thickness of the casing in the above-described facsimile apparatus, the roll recording paper KR is disposed between the reading section and the recording section. As a result, it is necessary that the dimensions of the case in the depth direction be made at least large enough to accommodate the roll recording paper KR. Therefore, a problem which arises is that the apparatus cannot be made small in the depth direction.
In order to realize a portable facsimile apparatus, downsizing each constituent unit of the apparatus if of paramount importance. Accordingly, with regard first of all to the size of the recording section in the width direction, the minimum required elements are two in number, namely the recording head and the side plates that are for freely rotatably supporting the conveyance roller. An arrangement in which one side plate of the main body, the head and the other side plate of the main body are arranged in the order mentioned in the width direction provides the smallest positioning mechanism.
More specifically, in the conventional facsimile apparatus described above, the side plate 40a of the main body, the head supporting 143a, the head 140, the head supporting member 143b and the side plate 40b of the main body are arranged in the order mentioned in the width direction of the recording section. The thickness of the head supporting members 142 and the dimensions of the clearances needed for installing them are large. This makes it necessary extra width for the relative positioning mechanism of the portable facsimile apparatus.
Further, when the elastic modulus of bending of the thermal head is compared with that of the conveyance roller in the conventional facsimile apparatus, the coefficient of the thermal head is about four times that of the conveyance roller. Therefore, in the case where the thermal head is biased with respect to the conveyance roller by the biasing members, the spring biasing force is high even though the three points are biased solely by the compression springs 120. As a consequence, the conveyance roller adapts itself to the head shape even though the head is in the flexed state so that the thermal head is uniformly biased in its axial direction.
However, in consideration of downsizing as mentioned above, it is better to use a thin-type thermal head that has half the thickness of the conventional apparatus. In such case the elastic modulus of bending of the thermal head will be 1/8 of the conventional apparatus. If this thin-type head is biased by the compression coils spring 120 at the three points in the same way as mentioned above and, moreover, it is biased at a biasing force of 1.5 kg, which is half that conventionally, the roller 150 will not adapt itself to the shape of the thin thermal head 140. Rather, the thermal head 140 having the low elastic modulus of curvature will adapt itself to the shape of the roller 150.
At such time, when use is made of the head 140 which is in the downwardly flexed state because of use of the compressed coil springs 120 to achieve biasing at three points, the two ends of the head 140 float free of the roller 150. The problem that results is that uniform biasing cannot be achieved in the axial direction, which is indicated by arrow y.
Further, in order to reduce the thickness of the casing in the above-described facsimile apparatus, the roll recording paper KR is disposed between the reading section and the recording section. As a result, it is necessary that the dimensions of the case in the depth direction be made at least large enough to accommodate the roll recording paper KR. Therefore, a problem which arises is that the apparatus cannot be made small in the depth direction.
In accordance with the above-described facsimile apparatus, only rolled recording paper is used as the recording paper; a thermosensitive recording paper in pre-cut sheets, such as size A4, cannot be introduced to the recording section. More specifically, in order to make it possible to introduce pre-cut sheets of recording paper to the recording section, a very troublesome operation is required, such as introducing the pre-cut sheets after the roll recording paper is removed first. This makes it substantially impossible to employ pre-cut sheets. In a case where a special-purpose opening for inserting pre-cut sheets is provided anew near the aforementioned first opening, by way of example, the strength of a rod-shaped partition formed between the first opening and the above-mentioned opening, which has a length at least as great as the A4 width of the pre-cut sheets, cannot be assured. This makes it substantially impossible to set pre-cut sheets in place.
Further, when the conveyance path of the recording paper and the conveyance path of the original are provided independently of each other, as in the illustrated facsimile apparatus, individual guide members must be provided. This is an impediment to downsizing. Further, since separate exit ports are also provided, it is difficult to assure the rigidity of the casing.
Furthermore, in accordance with the conventional facsimile apparatus, as shown in FIG. 26, a blade portion is formed as an integral part of the casing at the exit port 204 of the recording paper in order that the operator may tear off of the recording paper. However, since the casing is a part of the apparatus handled directly by the operator, the blade portion poses a hazard. This can lead to problems in terms of product liability (PL).